Power converters, such as DC-DC current mode power converters that convert an input voltage to a typically lower output voltage are known in the art. In DC-DC power converters, the output voltage is typically controlled using a feedback loop (feedback circuit) in dependence on an error voltage and an actual value of a current passing through an output device. Accordingly, control by the feedback loop requires sensing of the current passing through the output device. Sensing negative currents in addition to positive current passing through the output device generally poses a problem for the current sensing circuitry of such power converters.
In Prior art power converters, the current sensing circuitry is biased in class A by means of a bias current to enable sensing of negative currents. The bias current is chosen in accordance with the maximum negative current that is to be sensed. Accordingly, feedback loops of class A power converters dissipate a significant amount of power proportional to the bias current, even at zero load (quiescent current consumption).